High pressure intensifier system

ABSTRACT

A hydraulic pressure intensifier system ( 10 ) for developing a high pressure fluid jet that utilizes an electric motor ( 84 ) for both pressurizing a hydraulic fluid and for controlling the pressure and/or flow of the high pressure fluid jet developed by the system. The intensifier system also utilizes a return spring for retraction of the piston which allows the hydraulic fluid and the high pressure fluid to be separated by an air gap to minimize the potential for cross-fluid contamination. A high pressure hose ( 66 ) connected to the output of the intensifier includes a check valve ( 70 ) at its distal end rather than at the outlet of the intensifier to allow fluid to be drained out of the hose and into the intensifier upon system shut down for instantaneous stoppage of the jet.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/078,957 filed Jul. 8, 2008, which is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to pressure intensifiers and, more particularly, to pressure intensifiers for surgical and/or dental applications.

BACKGROUND

New technologies to replace traditional surgical cutting tools such as scalpels and drills are in high demand. Laser-based tools, electrosurgical cutters, plasma jets, and fluid jets have all been introduced to improve various surgical and medical procedures. Fluid jet cutters have several characteristics that make it a popular technology. For example, there is little heat generated by fluid jets (as compared to a drill or laser, for example) and the effects of fluid jets can be extremely localized.

Fluid jet cutters also excel at removing soft tissue due to the fact that high pressure jets tend to emulsify soft tissue and the emulsified tissue is easily transported by aspiration away from the surgical site. In contrast, competing technologies such as laser cutters and electrosurgical cutters remove tissue by ablation or electrothermal dissolution. Both of these effects tend to create collateral thermal damage and necrosis, which is generally unwanted and often intolerable for medical purposes. Accordingly, fluid jets have been employed for performing a variety of medical and/or dental procedures.

For example, using a fluid jet to excise, emulsify, and aspirate soft tissue can be useful for some dental procedures. One feature of a fluid jet that makes it well suited to such dental procedures is that the high velocity liquid jet can be used to easily remove soft tissue, but is limited in its ability to cut or erode hard calcified tooth tissue.

Existing fluid jet cutters generally include a high pressure intensifier for developing the high pressure fluid stream. Such intensifiers are typically pneumatically operated devices that include a T-shaped intensifier piston having a broad end which divides a drive bore into an actuating chamber and a retracting chamber. A bistable valve is connected to admit compressed air from an external source into the actuating chamber for driving the piston to translate. The narrow end of the piston is disposed in a fluid pumping chamber that is connected to a supply of fluid. The translating piston drives the fluid from the pumping chamber through a first check valve into a fluid jet nozzle which directs the high pressure fluid pulse to a tissue target. The bistable valve then switches to admit compressed air to the retracting chamber for driving the piston in reverse and allowing the pumping chamber to refill with fluid through a second check valve.

SUMMARY

The present invention provides intensifier systems for developing a high pressure fluid jet that utilize an electric motor. According to one aspect, a hydraulic pressure intensifier system for developing a high pressure fluid jet utilizes an electric motor for both pressurizing a hydraulic fluid and for controlling the pressure and/or flow of the high pressure fluid jet developed by the system. The intensifier system can also utilize a return spring for retraction of the piston which allows the hydraulic fluid and the high pressure fluid to be separated by an air gap to minimize the potential for cross-fluid contamination. A high pressure hose connected to the output of the intensifier includes a check valve at its distal end rather than at the outlet of the intensifier to allow fluid to be drained out of the hose and into the intensifier upon system shut down for instantaneous stoppage of the jet and/or to prevent contaminated fluid from being sucked into the hose.

A high pressure intensifier system in accordance with the invention can be designed to create high pressure water but could also be used to create high pressure fluids besides just water. The system can employ an oil over water intensifier, using 1000 psi oil pressure to generate 10,000 psi water pressure, for example. A stepper motor, or other suitable motor which may be AC, DC, brushless, servo, etc., drives a hydraulic pump for creating hydraulic pressure to act on a hydraulic drive piston during pressurization. Operatively coupled to the hydraulic piston is the intensifier piston, such that when they are pushed forward during a delivery stroke (also referred to herein as an intensification or discharge stroke), high pressure water is created in a cavity of the intensifier. Oil pressure in the hydraulic cavity is controlled using a low pressure transducer installed either in the hydraulic circuit, or a high pressure transducer installed in the fluid circuit, which gives feedback information to a PID (proportional integral derivative) loop or the like. The system can include a hydraulic solenoid valve for opening and closing the oil pressure path from the pump outlet to the hydraulic piston to thereby control pressure cycles. A pressure relief valve can be provided in the hydraulic circuit for prevention of system over-pressurization. The intensifier system can employ a spring to return the pistons back after reaching the end of the delivery stroke thereby allowing the intensifier cavity to refill with water (or other fluid to be intensified such as oil, saline solution, etc.) and be ready for another pressure intensification stroke. As will be appreciated, a two piston design can be provided in order to achieve continuous flow of high pressure water.

A high pressure hose or the like can be attached to the end of the intensifier via suitable fittings for receiving and transferring the high pressure fluid to a point of use. At a distal end of the hose a check valve can be provided for preventing fluid from reversing direction and returning to the intensifier cavity. Such check valve can be especially useful during the recharge stroke (also referred to herein as a retraction stroke) when the intensifier piston is retracting and fluid is refilling the intensifier cavity as it will prevent backflow of fluid. In addition, after a delivery stroke any accumulated pressure in the hose can be dissipated back into the intensifier chamber upon release of hydraulic pressure resulting in extremely quick pressure shut-off at the end of the hose. This can reduce or eliminate contamination of the hose and/or intensifier cavity, and also can serve to maintain fluid in the hose that is ready for dispensing on the next delivery stroke such that the hose need not be primed thereby allowing very rapid pressure ramp-up.

Accordingly, a pressure intensifier for developing a high pressure flow of fluid comprises a high pressure intensifier piston displaceable within a chamber of a high pressure intensifier cylinder between first and second positions to respectively discharge pressurized fluid from the chamber through an outlet on a delivery stroke and to intake fluid into the chamber through an inlet on a recharge stroke. A low pressure drive piston is supported for sliding movement within a low pressure cylinder and operatively coupled with the high pressure intensifier piston for displacing the high pressure intensifier piston towards the second position during the delivery stroke. A return spring is operatively coupled to at least one of the high pressure piston and the low pressure piston and configured to urge at least the high pressure piston towards the first position during the recharge stoke.

More particularly, a sleeve can be operatively coupled to the low pressure piston for movement therewith and adapted for telescoping movement over an exterior surface of the high pressure intensifier cylinder during displacement of the high pressure piston by the low pressure piston. The return spring can at least partially surround the sleeve, with the sleeve thereby acting as a spring guide for guiding the spring during movement of the pistons. The sleeve, the low pressure piston, and the high pressure intensifier cylinder can together form therebetween a void that can vary in size depending on the position of the low pressure piston. The void can separate the fluid acting on the low pressure piston from the fluid in the high pressure intensifier cylinder to avoid mixing of the same. The return spring can be interposed between the low pressure piston and the high pressure intensifier cylinder and can be configured to be compressed during the delivery stroke when the low pressure piston is displaced towards the high pressure intensifier cylinder. The high pressure intensifier cylinder can be supported within the low pressure cylinder, and the intensifier can be used for intensifiying the pressure of a stream of fluid including water.

In accordance with another aspect, a pressure intensifier system for developing a high pressure flow of fluid comprises a high pressure intensifier piston displaceable within a chamber between first and second positions to respectively discharge pressurized fluid from the chamber through an outlet on a delivery stroke and to intake fluid into the chamber through an inlet on a recharge stroke. A low pressure drive piston is supported for sliding movement within a cylinder and operatively coupled with the high pressure intensifier piston for displacing the high pressure intensifier piston towards the second position during the delivery stroke in response to pressurized fluid being supplied thereto. The system also includes a pump for supplying pressurized fluid to the low pressure drive piston, a motor for driving the pump, and a controller configured to control the motor in response to pressure sensed by a pressure sensor that senses the pressure of the pressurized flow. Alternatively, the controller could be configured to control the motor in response to pressure sensed by a pressure sensor that senses pressure in the hydraulic circuit.

The controller can be configured to control a speed or torque output of the motor to modulate the pressure of the pressurized flow. The system can include an electrical limit switch associated with the low pressure drive piston that is configured to limit the advance of the low pressure drive piston on the delivery stroke. A conduit fluidly coupled to the outlet for receiving the pressurized fluid from the chamber can be provided, the conduit having at a distal dispensing end thereof a check valve permitting flow through the conduit from the chamber and restricting backflow into the conduit. This prevents contamination of the conduit when pressure is shut off, and also allows pressure remaining in the conduit to be bled back to the chamber.

In accordance with another aspect, a pressure intensifier system for delivering a fluid comprises an intensifier unit for developing a high pressure flow of fluid, the unit including a high pressure piston displaceable within an intensifier chamber to discharge pressurized fluid through an outlet on a delivery stroke, and on a recharge stroke to admit fluid into the chamber through an inlet to refill the chamber, and a fluid conduit fluidly coupled to the outlet of the intensifier chamber for receiving high pressure fluid from the intensifier unit and for dispensing high pressure fluid at a dispensing end thereof connectable to a nozzle. The fluid conduit has a check valve at the dispensing end thereof remote the outlet for restricting backflow of fluid into the conduit when fluid is not being dispensed therefrom. A nozzle can be provided connected to the conduit, wherein the check valve restricts backflow of fluid from the nozzle into the conduit. The check valve can be a ball check valve or any other suitable type of check valve. An inlet check valve for restricting flow of fluid from the chamber out the inlet during the delivery stroke, and to permit flow of fluid through the inlet during the recharge stroke, can also be provided.

In an exemplary embodiment, a linear actuator is operatively coupled to the high pressure intensifier piston for advancing the piston on the delivery stroke and retracting the piston on the recharge stroke. The linear actuator can include a ball screw assembly, wherein, for example, the output shaft has a screw portion having threads threadedly engaged with mating threads associated with the high pressure piston, and wherein the high pressure piston is fixed against rotation such that rotation of the output shaft in a first direction advances the piston and rotation of the shaft in an opposite direction retracts the piston. A controller can be configured to control the motor in response to sensed condition, such as a pressure sensed by a pressure sensor that senses the pressure of the high pressure fluid, or a position of the linear actuator.

Further features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary pressure intensifier system in accordance with the invention.

FIG. 2 is a perspective view of an exemplary pressure intensifier assembly in accordance with the invention.

FIG. 3 is a top view of the pressure intensifier assembly of FIG. 2.

FIG. 4 is an end view of the pressure intensifier assembly of FIG. 2.

FIG. 5 is a cross-sectional view of the hydraulic circuit portion of the pressure intensifier assembly taken along the line A-A in FIG. 4.

FIG. 6 is another end view of the pressure intensifier assembly.

FIG. 7 is a cross-sectional view of the pressure intensifier assembly taken along the line B-B in FIG. 6.

FIG. 8 is a cross-sectional view taken through an axial length of an exemplary hose assembly connectable to an outlet of the pressure intensifier assembly.

FIG. 9 is a perspective view of an exemplary dual intensifier unit assembly for providing a continuous flow of intensified fluid.

FIG. 10 is a perspective view of another exemplary pressure intensifier assembly having a screw drive in accordance with the invention.

FIG. 11 is a cross-sectional view of the pressure intensifier assembly of FIG. 10.

FIG. 12 is a perspective view of an exemplary dual head screw drive pressure intensifier assembly in accordance with the invention.

FIG. 13 is a cross-sectional view of the exemplary pressure intensifier assembly of FIG. 12.

FIG. 14 is a perspective view of an exemplary dual intensifier unit assembly in accordance with the invention.

DETAILED DESCRIPTION

In FIG. 1, a pressure intensifier system for delivering a high pressure stream of fluid is indicated generally by reference numeral 10. The system 10 generally includes a hydraulic circuit 12 for generating hydraulic pressure to act on a piston for pressurizing a fluid, such as water, in a fluid circuit 14. In the following description the fluid of the fluid circuit 14 is water, but it will be appreciated that other fluids and/or suspensions can be pressurized by the intensifier without departing from the scope of the invention.

The hydraulic circuit 12 includes a pump 16 driven by a motor 20 for pumping hydraulic fluid from a reservoir 24. The pump 16 can be a fixed displacement pump, for example, configured to draw hydraulic fluid from the reservoir 24 through a filter 28 and supply the fluid via a pump outlet 30 to an outlet conduit 32 that is connected to a hydraulic cylinder 36. The outlet conduit 32 is also connected back to an inlet 38 of the pump 16 via a normally open solenoid valve 40. In addition, a pressure relief valve 44 connects the outlet of the pump 16 back to the pump inlet 38 for relieving pressure from the hydraulic circuit 12 in the event of overpressurization.

In operation, the motor 20 drives pump 16 to supply hydraulic fluid to outlet conduit 32. Since solenoid valve 40 is normally open, fluid in the outlet conduit 32 will be redirected back to the inlet 38 of the pump 16 until such time as the solenoid valve 40 is closed. Accordingly, until solenoid valve 40 is closed, little or no pressure is developed in outlet conduit 32. Once the solenoid valve 40 is closed, pressurized fluid in the outlet conduit 32 is supplied to a hydraulic chamber 46 in hydraulic cylinder 36 and acts on a hydraulic drive piston 48. As will be described in more detail below, the normally open solenoid valve 40, which may be electronic, provides automatic shutoff of the intensifier if the power fails, operator turns off system, etc., since the hydraulic circuit 12 of the system 10 is very quickly depressurized when the solenoid valve 40 is open. Response time of the solenoid can be about 40 milliseconds, for example.

As will be appreciated, when the solenoid valve 40 is closed, the pressurized fluid in the hydraulic circuit 12 acts on the hydraulic drive piston 48 causing a linear translation of the piston 48 to thereby displace an intensifier piston 52 in order to pressurize the fluid in the fluid circuit 14. The fluid circuit 14 includes a fluid reservoir 54 for holding a supply of fluid to be pressurized. The fluid reservoir 54 is connected to intensifier cylinder 58 in which intensifier piston 52 is supported. An inlet check valve 62 is configured to permit flow from the fluid reservoir 54 to the intensifier cylinder 58 and restrict backflow of fluid from the intensifier cylinder 58 to the fluid reservoir 54. The intensifier cylinder 58 has an outlet 64 to which a first end of a high pressure hose 66 is attached. A distal end of the high pressure hose 66 remote from the intensifier cylinder 58 includes an outlet check valve 70 for restricting backflow of pressurized fluid into the hose from a nozzle 74.

During operation of the fluid circuit 14 on a delivery stroke, the intensifier piston 52 is translated from the left to the right in FIG. 1 as hydraulic fluid acts on the hydraulic drive piston 48. The intensifier piston 52 acts on fluid in the intensifier cylinder 58 thereby compressing the fluid. The fluid is then supplied via intensifier cylinder outlet 64 to hose assembly 126 for delivery to a target location via hose outlet or nozzle 74. Upon completion of the delivery stroke, a retraction stroke commences in which hydraulic fluid is no longer applied to the hydraulic drive piston 48 and solenoid valve 40 is opened thereby allowing both the hydraulic drive piston 48 and the intensifier piston 52 to translate back to the left in FIG. 1. To effect retraction, a spring or the like can be provided as will be described. In addition, pump 16 and motor 20 can be reversible for assisting in removing hydraulic fluid from the hydraulic chamber 46.

During the retraction stroke, outlet check valve 70 prevents backflow of fluid from the nozzle 74. Accordingly, as negative pressure builds within the intensifier chamber 63, fluid from the fluid reservoir 54 is drawn into the intensifier cylinder 58 via inlet check valve 62. Upon completion of the retraction stroke, another delivery stroke can commence and the process can then repeat.

As will be described in more detail below, a controller 80 can be provided for controlling the motor 20 in response to pressure sensed in the hydraulic circuit 12 by a pressure transducer 82 and/or pressure sensed in the fluid circuit 14 by pressure transducer 84.

Turning now to FIGS. 2-8, and initially to FIG. 2, an exemplary high pressure intensifier system assembly is generally indicated by reference numeral 110. The intensifier assembly 110 has a housing 114 in which both hydraulic circuit components and fluid circuit components, for example as shown and described in connection with FIG. 1, are housed. A fluid inlet port 118 is provided for connection to a fluid reservoir and a high pressure fluid outlet port 64 is provided for connection to a hose assembly 126 which includes the hose 66 and outlet check valve 70 at a distal end thereof (not shown in FIG. 2). The intensifier assembly 110 is designed such that the intensifier portion can be quickly replaced as a unit for replacement or repair.

With reference to FIGS. 3 and 4, the intensifier assembly 110 generally includes two parts, the hydraulic pump system portion 130 (e.g., including the hydraulic circuit 12) and the intensifier assembly portion 134 (e.g., including the fluid circuit 14). The pump system portion 130 generally includes the hydraulic circuit components including the motor 20, pump 16, solenoid valve 40, outlet conduit 32, etc., shown in FIG. 1. A gasket, such as bellows gasket 141, moves in response to changes in hydraulic oil level in reservoir 24 during system operation thereby allowing the pump portion of the assembly to be a closed hydraulic circuit. The intensification assembly portion 134 generally includes the components of the fluid circuit 14 of FIG. 1 including the inlet check valve 62, the intensifier cylinder 58, etc.

Turning to FIG. 5, which is a cross-section taken along the line A-A in FIG. 4, the internal details of the pump system portion 130 of the intensifier system assembly 110 are shown. In particular, motor 20 includes motor shaft 140 operatively connected to pump 16. Pump 16 receives fluid from pump inlet 38 and supplies fluid to the pump outlet 30. Pump outlet 30 is connected to the outlet conduit 32 which supplies fluid to the hydraulic cylinder 36 (not shown in FIG. 5). Solenoid valve 40 connects the outlet conduit 32 back to the pump inlet 38, and relief valve 44 is provided to relieve pressure from the outlet conduit 32 in the manner previously described.

In FIGS. 6 and 7, the internal details of the pressure intensifier assembly 134 are shown. FIG. 6 is an end view of the pressure intensifier assembly 134. FIG. 7, which is a cross-section taken along the line B-B in FIG. 6, shows the hydraulic drive piston 48 supported for sliding axial movement within hydraulic cylinder 36. Opposite the hydraulic piston 48, an intensifier cylinder 58 is supported within the hydraulic cylinder 36 and receives the intensifier piston 52 which is operatively coupled to the hydraulic piston 48 for movement therewith.

The intensification assembly portion 134 is secured to the hydraulic cylinder 36 via a quick-release mechanism 136 which includes locking balls 137, a release collar 138, and a spring 135. As will be appreciated, the locking balls 137 and release collar 138 cooperate to lock and/or release the intensification assembly 134 from the hydraulic cylinder 36. In the locked position of FIG. 7, the release collar 138 restricts radial expansion of the locking balls 137 thus preventing withdrawal of the intensification assembly 134 from the hydraulic cylinder 36. Likewise, the spring 135 prevents accidental release of release collar 138 by biasing the collar towards the lock position. To release the intensification assembly 134 for withdrawal, release collar 138 is shifted rightward in FIG. 7 against the bias of spring 135 such that the locking balls 137 can expand radially into an annular groove 139 in the release collar 138 thereby permitting the intensification assembly 134 to be withdrawn from the hydraulic cylinder 36. The quick-release mechanism 136 allows the intensification assembly 134 to be quickly and easily removed for repair or replacement.

A cylindrical sleeve 142 surrounds a portion of an exterior surface of the intensifier cylinder 58 and is configured to slide axially with the hydraulic drive piston 48 upon movement thereof during a delivery stroke as previously described. A return spring 144 is interposed between a radially outwardly extending shoulder 146 of the sleeve 142 and a radially outwardly extending shoulder 148 formed in an outer surface of the intensifier cylinder 58. The return spring 144 is configured to be compressed during the delivery stroke and, upon a decrease in pressure in the hydraulic chamber 46 at the end of the delivery stroke, the return spring 144 is configured to act against the hydraulic drive piston 48 and/or intensifier piston 52 to carry out the retraction stroke. Unlike other intensifier systems that use hydraulic pressure to both extend and retract a hydraulic piston, the present embodiment facilitates automatic return of both pistons upon removal of the application of pressurized fluid to the hydraulic piston 48. Further, providing the spring 144 over the outside of the intensifier cylinder 58 saves space by reducing over all system length.

As will be appreciated the hydraulic drive piston 48 includes one or more seals 152 for sealing the piston 48 to the hydraulic cylinder 36. Similarly a high pressure seal 156 is provided for sealing the intensifier piston 52 to the intensifier cylinder 58. A pair of bushings 158 stabilize the intensifier piston 52 as it slides axially.

As it is generally desirable to prevent mixing of the hydraulic fluid with the fluid in the fluid circuit 14, an air gap 160 is provided between the hydraulic chamber 46 containing the hydraulic fluid and the intensifier chamber 63 containing the fluid to be pressurized. Accordingly, hydraulic fluid does not contact the intensifier piston at any time, unlike other intensifiers that have hydraulic fluid pushing an intensifier piston in both directions and hydraulic fluid in direct contact with the intensifier piston.

The air gap 160 also serves at least two functions related to preventing mixing of the hydraulic fluid and the fluid in the intensifier chamber. First any leakage past either seals 152 or 156 into the air gap 160 can be drained out of the assembly via suitable drain ports, such as drain hole 166, rather than result in mixing of the fluids. Second, the air gap 160 can make detection of a leak easier since, under normal operation, no fluid (hydraulic or otherwise) will exist in the air gap 160. Thus, if fluid is detected in the air gap 160 one or more of the seals is likely leaking. Accordingly, a sight glass could be provided in place of, or in addition to, the drain hole 166 to facilitate detection of fluid in the air gap 160. Alternatively, or in addition, one or more sensors could be provided for sensing the presence of fluid in the air gap 160. The air gap 160 also prevents high pressure fluid from spraying out of the intensifier in the event the high pressure seals leak or otherwise fail.

As previously described, in operation of the assembly pressurized hydraulic fluid is provided to the hydraulic cavity chamber 46 and acts upon hydraulic drive piston 48 to displace hydraulic drive piston 48 leftward in FIG. 7. The displacement of hydraulic piston 48 results in a corresponding displacement of the intensifier piston 52 which acts on fluid in the intensifier chamber 63 thereby pressuring such fluid. The inlet check valve 62 prevents fluid from escaping from the intensifier chamber 63 back to the reservoir 54 such that the pressurized fluid is forced into the hose assembly 126 for dispensing at a target.

When the hydraulic drive piston 48 reaches full extension, pressure in the hydraulic circuit 12 is released via the opening of solenoid valve 40. A limit switch on the hydraulic cylinder 36 can be provided for sensing such position of the drive piston 48 and automatically opening the solenoid valve 40. The limit switch can be an electronic limit switch, for example, as opposed to the mechanical switches used on many hydraulic intensifiers. Such switch can be tripped by a magnet 168 integrated into the hydraulic piston 48, or could also be a linear strip such that the system has variable full pressure time.

Upon release of the hydraulic pressure on hydraulic piston 48 (e.g., via opening of solenoid valve 40), the spring 144 forces the hydraulic piston 48 and intensifier piston 52 rightward in FIG. 7 thereby drawing fluid into the intensifier chamber 63 from the reservoir 54 through inlet 118 (see FIG. 6) in preparation for a new intensification stroke. As noted, the pump 16 and motor 20 can be reversible to assist in removal of hydraulic fluid from the hydraulic chamber 46 during the retraction stroke.

Turning to FIG. 8, the hose assembly 126 is shown in detail. The hose assembly 126 generally comprises a conduit 170 through which the pressurized fluid can flow, a hose nut 174 for coupling the conduit 170 to an outlet 64 of the intensifier pressure chamber, and a fitting 178 such as a quick disconnect fitting for coupling the conduit 170 to a hand tool or the like. Outlet check valve 70 is provided at the distal end of the conduit 170 remote from the intensifier chamber and acts to prevent backflow of fluid from downstream of the valve 70 from being drawn back into the conduit 170 on the retraction stroke of the intensifier assembly 134.

Referring back to FIG. 1, it will be noted that the output of the motor 20 can be controlled to control the pressure and/or flow output of the intensifier. To this end, a PID loop (proportional integral derivative) or PI loop, for example, can be configured to control the speed of the motor 20, which then controls the flow rate and/or pressure of the output of hydraulic pump 16, which in turn controls the flow rate and/or pressure of output of the intensified fluid dispensed from the intensifier chamber 63 and/or hose 66.

In this regard, pressure transducer 84 is provided for sensing the pressure of the pressurized fluid in fluid circuit 14 and generating a signal in response thereto. This signal is then fed to the controller 80 configured to control the motor 20 in response to the sensed pressure in order to deliver a desired pressure. For example, if the sensed pressure is below a desired pressure, the controller 80 will ramp up the speed of the motor 20 in order to increase the pressure applied to the hydraulic drive piston 48 and, in turn, to the intensifier piston 52. If the sensed pressure is greater than the desired pressure, the controller 80 will decrease the speed of the motor 20 in order to decrease the pressure of the pressurized fluid. Accordingly, the system 10 acts essentially as a proportional hydraulic system but without a proportional control valve.

It will be appreciated that pressure and/or flow of either the hydraulic circuit 12 (via pressure transducer 82) and/or the fluid circuit 14 (via pressure transducer 84) could be used for providing feedback to control the motor 20. Further, both the speed and/or torque output of the motor could be used to achieve a desired output pressure and/or flow.

Turning to FIG. 9, a dual intensifier assembly for providing a continuous intensified flow of fluid is indicated generally by reference numeral 200. As will be appreciated, the unit 200 is essentially two systems, as described in FIGS. 1-8, joined together. The unit 200, thus, includes first and second intensifier assemblies 202 and 204 each having a hydraulic assembly portion and an intensifier assembly portion as previously described. Although not shown, the units 202 and 204 can share a common housing.

By alternating the delivery strokes of each intensifier assembly 202 and 204, the unit 200 can supply a continuous intensified flow of fluid through a hose assembly or the like for dispensing at a target. Suitable controls can be provided for ensuring that when one assembly is on a retraction stroke, the other assembly is on a delivery stroke such that high pressure fluid is always available to be dispensed. The outlets of each unit may be fluidly coupled to a manifold to which a hose assembly as herein described is also attached, for example.

It will further be appreciated that the hydraulic circuit as described above could be replaced by an electromechanical device for providing the linear velocity and force to create the intensified fluid. For example, a suitable electromechanical device could be an integrated motor (servo, etc) configured to turn a ball screw or the like for advancing the intensifier piston.

Turning to FIGS. 10-14, and initially to FIG. 10, an exemplary intensifier assembly having a screw drive (e.g., a ball screw assembly) in accordance with the invention is indicated generally by reference numeral 300. The assembly 300 generally includes a cylinder body 304 to which an intensifier portion 308 is coupled via a quick-release mechanism 310 or the like, and a motor 312 for driving the intensifier. As will be described below, the motor 312 in this embodiment replaces the hydraulic circuit for supplying the power to actuate the intensifier piston. The intensifier portion 308 is generally similar to the above-described intensifiers with respect to the manner in which fluid is drawn into the intensifier chamber via an inlet 316, pressurized by the intensifier piston, and delivered to the outlet 320. Accordingly, the details of the intensifier portion will not be described.

Turning to FIG. 11, the internal features of the intensifier assembly 300 are shown. As mentioned, the intensifier portion 308 is generally similar to the previously described intensifier assemblies and includes an intensifier piston 324 movable within intensifier chamber 328 between first and second positions for drawing fluid into the chamber 328 and intensifying the pressure of the fluid for dispensing via outlet 320.

In this embodiment, the intensifier piston 324 is operatively coupled to a motor shaft screw of 332 of the motor 312 such that rotation of the screw 332 in a first direction advances the intensifier piston 324 and rotation of the screw 332 in the opposite direction retracts the intensifier piston 324. To this end, the intensifier piston 324 has a bore having internal threads 336 threadedly engaged with external threads 340 of the screw 332. The intensifier piston 324 can be fixed against rotation and supported for sliding axial movement within the cylinder body 304 by a retainer 344 and a bushing 348.

Accordingly, as the motor 312 spins the screw 332 in a first direction, the intensifier piston 324 is advanced within the intensifier chamber 328 to thereby discharge pressurized fluid in the manner previously described. Upon completion of such intensification stroke, the motor is reversed to thereby retract the intensifier piston 324 to refill/recharge the intensifier chamber 328 with fluid for the next intensification stroke.

In the illustrated embodiment, the speed and/or torque of the motor 312 can be controlled in order to deliver a desired pressure. In this regard, a pressure transducer 352 (see FIG. 10) can be provided for sensing the pressure of the pressurized fluid, and feeding a signal indicative of the pressure to a controller for controlling the current supplied to the motor 312. As will be appreciated, limit switches can be used to set the stroke of the intensifier piston within the chamber.

Turning now to FIGS. 12 and 13, a continuous flow dual head screw pump intensifier assembly is generally indicated by reference numeral 400. In this embodiment, a pair of intensifiers 308 are alternately driven by a screw shaft of a motor 312 to thereby supply a continuous flow of intensified fluid.

Referring to FIG. 13, it will be appreciated that in this embodiment a single motor 312 drives a pair of intensifier assemblies 308 coupled to respective cylinder bodies 304 via respective quick-release couplings 310, for example. Accordingly, rotation of the screws 332 in a first direction advances one of the intensifier pistons 324 while retracting the other intensifier piston 324. Reversing the rotation of the screws 332 reverses the movement of the respective pistons 324. Thus, while one intensifier piston is on an intensification stroke, the other piston is on a recharge. The screws 332 can be part of a common shaft driven by the motor 312.

Turning now to FIG. 14, a dual intensifier assembly 500 is illustrated. In this embodiment, the dual intensifier assembly 500 includes two individual intensifier units 300 as described in connection with FIGS. 10-11, each having a respective motor 312. To provide a continuous flow of intensified fluid during operation, one intensifier unit is configured to operate on an intensification stroke while the other intensifier unit is on a recharge stroke.

Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application. 

1. A pressure intensifier for developing a high pressure flow of liquid comprising: a high pressure liquid intensifier piston displaceable within a chamber of a high pressure intensifier cylinder between first and second positions to respectively discharge pressurized liquid from the chamber through an outlet on a delivery stroke and to intake liquid into the chamber through an inlet on a recharge stroke; a low pressure hydraulic drive piston supported for sliding movement within a low pressure cylinder and operatively coupled with the high pressure intensifier piston for displacing the high pressure intensifier piston towards the second position during the delivery stroke; and a return spring operatively coupled to at least one of the high pressure piston and the low pressure piston and configured to urge at least the high pressure piston towards the first position during the recharge stoke.
 2. A pressure intensifier as set forth in claim 1, further comprising a sleeve operatively coupled to the low pressure piston for movement therewith, the sleeve adapted for telescoping movement over an exterior surface of the high pressure intensifier cylinder during displacement of the high pressure piston by the low pressure piston.
 3. A pressure intensifier as set forth in claim 2, wherein the return spring at least partially surrounds the sleeve, the sleeve thereby acting as a spring guide for guiding the spring during movement of the pistons.
 4. A pressure intensifier as set forth in claim 2, wherein the sleeve, low pressure piston, and high pressure intensifier cylinder together form an air gap that can vary in size depending on the position of the low pressure cylinder, whereby the air gap separates hydraulic fluid acting on the low pressure piston and liquid in the high pressure intensifier cylinder.
 5. A pressure intensifier as set forth in claim 1, wherein the return spring is interposed between the low pressure piston and the high pressure intensifier cylinder, the spring being configured to be compressed during the delivery stroke when the low pressure piston is displaced towards the high pressure intensifier cylinder.
 6. A pressure intensifier as set forth in claim 1, wherein the high pressure intensifier cylinder is supported within the low pressure cylinder.
 7. A pressure intensifier as set forth in claim 1, wherein the pressurized liquid includes water.
 8. A pressure intensifier system for developing a high pressure flow of fluid comprising: a high pressure intensifier piston displaceable within a high pressure chamber between first and second positions to respectively discharge high pressure fluid from the chamber through an outlet on a delivery stroke and to intake fluid into the chamber through an inlet on a recharge stroke; a low pressure drive piston displaceable within a low pressure chamber separate from the high pressure chamber, the low pressure drive piston being supported for sliding movement within a cylinder including the low pressure chamber and operatively coupled with the high pressure intensifier piston for displacing the high pressure intensifier piston towards the second position during the delivery stroke in response to low pressure fluid being supplied thereto; a pump for supplying the low pressure fluid to the low pressure drive piston; a motor for driving the pump; and a controller configured to control the motor in response to pressure sensed by a pressure sensor that senses the pressure of at least one of the high pressure fluid or the low pressure fluid.
 9. A pressure intensifier system as set forth in claim 8, wherein the controller controls a torque output of the motor to modulate the pressure of at least one of the high pressure fluid or the low pressure fluid.
 10. A pressure intensifier system as set forth in claim 8, wherein the controller controls a speed output of the motor to modulate the pressure of at least one of the high pressure fluid or the low pressure fluid.
 11. A pressure intensifier system as set forth in claim 8 further comprising an electrical limit switch associated with the low pressure drive piston the limit switch configured to limit the advance of the low pressure drive piston on the delivery stroke.
 12. A pressure intensifier system as set forth in claim 8, further comprising a conduit fluidly coupled to the outlet for receiving the high pressure fluid from the chamber, the conduit having at a distal dispensing end thereof a check valve permitting flow through the conduit from the chamber and restricting backflow into the conduit.
 13. A pressure intensifier system as set forth in claim 8, wherein the fluid includes water.
 14. A pressure intensifier system for delivering a fluid comprising: an intensifier unit for developing a high pressure flow of fluid, the unit including a high pressure piston displaceable within an intensifier chamber to discharge high pressure fluid through an outlet on a delivery stroke, and on a recharge stroke to admit fluid into the chamber through an inlet to refill the chamber; and a fluid conduit fluidly coupled to the outlet of the intensifier chamber for receiving the high pressure fluid from the intensifier unit and for dispensing the high pressure fluid at a dispensing end thereof connectable to nozzle; wherein the fluid conduit has a check valve at the terminal dispensing end thereof remote the outlet of the intensifier chamber for restricting backflow of fluid into the conduit when fluid is not being dispensed therefrom.
 15. A pressure intensifier system as set forth in claim 14, further comprising the nozzle, wherein the check valve restricts backflow of fluid from the nozzle into the conduit.
 16. A pressure intensifier system as set forth in claim 14, wherein the check valve is a ball check valve.
 17. A pressure intensifier system as set forth in claim 14, further comprising an inlet check valve for restricting flow of fluid from the chamber out the inlet during the delivery stroke, and to permit flow of fluid through the inlet during the recharge stroke.
 18. A pressure intensifier system as set forth in claim 14, further comprising a linear actuator operatively coupled to the high pressure intensifier piston for advancing the piston on the delivery stroke and retracting the piston on the recharge stroke.
 19. A pressure intensifier system as set forth in claim 18, wherein the linear actuator includes a ball screw.
 20. A pressure intensifier system as set forth in claim 19, wherein the output shaft has a screw portion having threads engaged with mating threads associated with the high pressure piston, and wherein the high pressure piston is fixed against rotation such that rotation of the output shaft in a first direction advances the piston and rotation of the shaft in an opposite direction retracts the piston.
 21. A pressure intensifier system as set forth in claim 14, further comprising a controller configured to control the motor in response to sensed condition.
 22. A pressure intensifier system as set forth in claim 21, wherein the sensed condition includes at least one of a pressure sensed by a pressure sensor that senses the pressure of the high pressure fluid, or a position of the linear actuator.
 23. A pressure intensifier system as set forth in claim 14, wherein the intensifier unit is removable from the intensifier assembly as a unit.
 24. A pressure intensifier system as set forth in claim 14, wherein the intensifier unit releasably attachable to the intensifier assembly.
 25. A pressure intensifier system as set forth in claim 14, wherein the intensifier unit is attached to the intensifier assembly by a quick-release mechanism. 